I have a misfire that I've narrowed down to either valve springs or ignition. I'm leaning more toward the distributor because it doesn't happen every time and the misfire pattern isn't the same. It typically occurs between 5500-6000 rpm. I run a stock HEI with computer controlled advance, .040 gap spark plugs, and 8mm wires. What distributor should I buy?

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1986 CAMARO Z28 -> 150,000 original miles, 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, reinforced LCA's w/bushings, Subframes connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH Next mods-> Adjustable panhard rod, LCA lowering brackets, homemade ram air, B&M shifter.

 

Don't buy a new dist., buy a new chip. Your chip limits your RPM range.

 

What about advancement? How do I know how much timing it is giving me? How is it going to be optimal?

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1986 CAMARO Z28 -> 150,000 original miles, 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, reinforced LCA's w/bushings, Subframes connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH Next mods-> Adjustable panhard rod, LCA lowering brackets, homemade ram air, B&M shifter.